Effect of Chromium Doping on The UV- and Sunlight-Driven Photocatalytic Performance of SrTiO3

Abstract

Chromium (Cr)-doped strontium titanate (SrTiO₃, STO) photocatalysts with compositions of SrTi1-xCrxO₃ (x = 0, 5, and 10%) were prepared via the coprecipitation method. This study aimed to investigate the effects of Cr doping on structural, morphological, and optical properties. Furthermore, this work aimed to examine the photocatalytic performance of pure and Cr-doped STO against methylene blue (MB) degradation under ultraviolet (UV) and sunlight exposure. X-ray diffraction confirmed the formation of the cubic STO phase and the insertion of the Cr dopant in the STO structures. Furthermore, Cr doping reduced the lattice constant, crystallite size, and average particle size and narrowed the band gap from 3.2 (STO) to 2.9 eV (STO:Cr10%). Photocatalytic evaluation via methylene blue degradation revealed contrasting behaviors under different irradiation sources. Under UV irradiation, STO:Cr10% exhibited the highest degradation efficiency (57.23%), whereas under natural sunlight, pure STO showed superior activity (97.15%) compared with Cr-doped samples. These findings indicate that while Cr doping enhances UV-driven photocatalytic activity by modifying the structure and morphology characteristics and narrowing the band gap, pure STO performs more efficiently under sunlight irradiation, possibly because of the absence of dopant-induced recombination centers.